Voice over Internet protocol (VoIP) implementations enable voice traffic, such as telephone calls, to be carried over Internet protocol (IP) communications networks. This allows voice calls to use the reduced transmission cost associated with packet switched networks to carry information once exclusively carried over more expensive conventional circuit switched networks. For example, during a VoIP call the voice signal from a user is compressed and packetized using one or more of a variety of applicable protocols so as to be suitable for being transmitted using a packet switched communications network to a called party. When the VoIP packets are received at their destination, the voice signal is decompressed before being played to the called party. The specific path that the packets take over the packet switched communications network is not specified and can be any suitable path that is available. Thus, a VoIP call between the same origin and destination may take different actual paths through the communications network.
As a result, voice call quality for VoIP calls may vary more than conventional calls transmitted using a circuit switched network. Specifically, speech quality of VoIP calls may be affected by factors such as delay, jitter, and packet loss. Additionally, service providers may enter into contracts with customers to provide specified levels of speech quality between specified end points.
In order to accurately quantify varying speech quality levels, many different measures of speech quality have been used for monitoring speech quality for VoIP calls. Consequently, both objective and subjective measures of voice quality have been developed to ensure that the specified voice quality is being met. Objective measures of speech quality, such as measures used for determining the number of packets dropped, can be utilized as an indicator of speech quality. However, because speech quality is perceived by human users rather than machines, subjective measures of speech quality have been developed. Subjective speech quality measures include, for example, a mean opinion score (MOS). A MOS for a call may be determined by the judgments of the voice quality of a call gathered from a wide range of listeners, and may be expressed on a scale of 1 (poor) to 5 (excellent).
Recently, an algorithm known as perceptual evaluation of speech quality (PESQ) has been developed and is capable of accounting for filtering, variable delay and short localized distortions of packetized voice calls. Hence, PESQ is a popular measure of end-to-end voice quality over packet switched networks. PESQ compares an original signal x(t) with a degraded signal y(t), which is the result of passing x(t) through a communications system. The output of PESQ is a prediction of the perceived quality that would be given to y(t) from subjects participating in a subjective listening test. When PESQ or similar algorithms are used to measure speech quality, a dedicated voice call is set up to transmit only test speech signals over a communications network. This enables the test voice signals to be easily identified and provides a means of determining the amount of degradation that occurs as a result of transmission over the network. PESQ provides an estimated MOS of the speech quality and is described in international telecommunications union (ITU) recommendation P.862, the contents of which are incorporated herein by reference in its entirety.
Although nearly all existing test call systems are adapted to make test calls to a telecommunications service provider's subscribers, a significant number of these systems lack the ability to dynamically characterize the customers and test associated subscriber device numbers accordingly. Instead, a network operator is compelled to manually monitor and analyze PESQ scores derived from the test call to determine if additional (or less) test call generation associated with a particular subscriber is necessary. After assessing that further call testing is not required, a network operator typically removes the subscriber device number from the test call list on a manual basis.
Accordingly, in light of these shortcomings, a need exists for improved methods, systems, and computer readable media for automatically categorizing voice over Internet Protocol (VoIP) subscriber devices in accordance with VoIP test and call quality data are disclosed.